OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines Rebuilding Black Betty with PICS!!!

Hi guys,
we've had this old and mistreated lawn mower for three or four years (bought from cash converters for $95) and although it's never run quite right, and is ear-bleedingly loud we're fond of its rugged charm

Now that our lawn has finally grown past the point of not only shrouding the house in mystery, but also devaluing house prices throughout our suburb I decided last weekend to sharpen up the blades, clean it up and have at it.
What started as a quick spruce-up led to dismantling almost everything and shooting a quick rattle-can coat of killrust on the engine cover, and ended late Sunday night with this:


Unfortunately we also have a delegation of neighbours, several logging trucks, 40 Ewoks with rope bridges between their huts and a wild rabble waving flaming torches camped in the street waiting for the lawn to be mowed. Despite being pampered and cleaned and reassembled haphazardly Betty refuses to play. B&S ID is as follows:
Model 92502, Type 0938-01, Code 78052501


Perhaps the crudely stuck on FORD logo has something to do with it:


Or PERHAPS it has something to do with the fact that when I reassembled it all I used no new parts. Frankly I had no new parts, so instead made do with welding and grinding and wire brushing old ones in order to make them look less filthy and dilapidated. One thing I found disturbing was the slow weeping of fuel from around the base of the carb gasket after I 'primed' it with a shot down the guts:


I get a cough and a couple of fires and then she goes back to sleep. idle/mixture screw thingum was wound out 2 turns, then 2.5 and then three to no avail. I used to be able to get her screaming and running quick enough by 'priming' and jamming the butterfly open with the aircleaner screw, but no dice.

Next step? points are clean, gap is 20 thou, fuel tank is cleaned out, fuel pickup tube screen thing is clear, aircleaner is... disgusting, but left off mainly
and oil has been changed for the first time since 25th may 1978.
Thinking of buying Diaphragm and this: [url=https://www.outdoorking-forum.com.au/bmz_cache/d/d844bb80cbb61e6752272cfe02a98188.image.320x320.jpg][/url]

but none of the model numbers line up with anything and I'm not sure if this is just going to be a waste of time.

Thoughts?

Here is the illustrated parts list:
http://bsintek.basco.com/BriggsDocumentDisplay/Z6kotCVJ1DajI.pdf

Here is the operator's manual:
http://bsintek.basco.com/BriggsDocumentDisplay/msowGK-K_ny7tH217FzoPu.pdf

A couple of points to start with. First, never try to run a VacuJet carburetor like yours, or especially a PulsaJet carburetor, without inserting the air cleaner retaining screw and screwing it in. Second, you do not seem to have followed an orderly process with your attempts to get it running, and this might have made your efforts futile. For example, it is very easy to make a 4 stroke too rich to run, and with the air cleaner screw not installed plus a random quantity of fuel poured into the carburetor air intake, you could easily have exceeded this limit.

I suggest you switch to an orderly process instead of a disorderly one. First, prepare the machine by inserting the air cleaner screw and setting the speed control in the start position. Remove the spark plug and pull the starter half a dozen times to begin the process of clearing out surplus fuel, if it has any.
Second, test for spark by connecting the plug wire to the plug (which has been removed from the cylinder head) and clamping the metal plug body to the cylinder head. Pull the starter and watch for a steady series of blue sparks across the plug gap. If you don't get this steady series, stop right there and fix the ignition system. If you do get satisfactory spark, reinstall the spark plug and connect it.
Third, you need to check whether the automatic choke is functioning correctly. Look down the bore of the carburetor and observe whether the choke is fully closed. If it is, pull the starter and see if it opens while the engine spins, then closes again as the engine stops spinning. If the choke isn't fully closed, you've wrecked it and will have to go through the carburetor overhaul procedure from the Briggs manual.
Fourth, check the compression. This means first, feel the resistance to pulling the starter. Second, disconnect the spark plug lead and tilt the mower so you can access the blade disk. Now check two or three more times that the spark plug is disconnected, before you go any further. Move the speed control to the stop position. Rotate the blade disk backwards until you find compression, approaching it from the wrong side. Then flip the disk backward toward compression, and see if it bounces back.

If you have functional spark, compression and choke, you are ready to start finding and fixing the fault. Please report back at that point.

Thanks Grumpy,
The manual and parts list will be very useful! I was hoping for more of a 'replace the carb to tank gasket' type of response, as the leakage seems to be the only thing that has changed since the haphazard rebuild. Although pouring random quantities of fuel down her throat to start her up is obviously not a very professional method, it HAS always worked very well in the past, hence my question.

Considering that Betty is (has always been) held together with bits of twisted wire, shoelaces and badly painted rust I figure any minor improvements and/or replacements that can be suggested by the experts on the forum here will be far better than the alternative (wife says take to tip, buy new mower). Although a rebore, valve job and forced induction are probably not on the cards anything that will return her to her former glory will be considered rather than consigning her to the scrap heap.

I have compression and I have spark, which leaves fuel. Maybe I'll just throw on a new gasket and try some fuel that ISN'T mixed with 2 stroke oil and is thirty years old and see if she wakes up again.

One more thing: I know it takes roughly 600ml of oil from DRY, but as my model has no dipstick is there a sight line to look for in the oil-fill threaded area which tells you if there's enough/too much? I drained the black pre-cambrian ooze and refilled with around 400mls of fresh honey-coloured mega oil.

The correct oil level is filled to the brim of the filler hole, on pre-dipstick Briggs engines. Then the oil expands when you run the engine, so you have to have tightened the plastic plug with a screwdriver or it will leak.

I can't help you with rough-and-ready attempts to get your engine running a bit. We don't do that here.

If I may ask, what exactly do you do here?

Outdoorking is a site where people can bring their outdoor machine problems and have discussions with members and moderators about putting them right. We aim to follow good service practice, for a whole lot of reasons ranging from safety concerns, to not wasting people's time and money by half-fixing their problems. That does not mean people need to replace parts that are within service wear limits, or throw away engines that cannot economically be restored to new condition. We are happy to talk about getting them to run as well as a worn engine can run. However bodged or haywired machines are approached with the aim of putting them right, not prolonging their unreliable, and often unsafe, performance.

Hi fingernails, grumpy is one of the moderator team of this forum, who is a four stroke small engine specialist.
His experience in helping many members rebuild basket-case engines is well documented in our archives. He is an experienced and valuable asset to OutdoorKing.

We pride ourselves here in helping our members achieve a good repair results, with the members help; also by them following the advice given, and using good, safe, workshop practices.

We do not encourage or condone unsafe or shoddy practices as that would reflect badly on our reputation as a repair site, especially if someone suffered an injury as a result.

If you want Black Betty up and running sweetly again, I respectfully encourage you to follow grumpy's advice carefully.
Kind Regards,
Deejay
Global Moderator OutdoorKing.

Excellent, I'm glad we're all on the same page here then. Perhaps somewhere along the line someone has misinterpreted exactly what it is that I am attempting, namely repairing and returning to service a lawnmower that HAS been shoddily bodged and haywired together in the past. I have no intention of jury-rigging wires and springs (like the PO has apparently done) which is why I have patronised this fine forum in my attempts to repair it and get it running as well as can be expected for a lawnmower that is roughly 35 years old and has no signs of ever having been looked after.

I have purchased the B&S carburettor overhaul kit from outdoorking.com and based on the information I have gleaned from various sources believe that this should cure the issue nicely; I was hoping that the description of the symptoms and condition of the parts in my original post would make it easier for the experts here to have a stab at diagnosing the fault, I did not expect to be told pompously to go somewhere else for assistance....

What the , I think its time for a manicure.

You have obviously taken offence....where no offence is implied or intended...what we want to achieve is a good result with your machine...If I have appeared to be pompous in my reply, I apologise....I just wanted you to understand where we are coming from when we give our advice to our members.
Fingernails, we don't want you to leave our site, in fact we would like to help you achieve a great outcome for your machine....but we need to work together to achieve that aim.....and grumpy can help you do that, if you follow his advice and realise he is giving of his time and experience, to help you..

I'm with roebuck on this one, I'll let this thread go through to the wicketkeeper. Others are welcome to join in and help the member of course, as always.

hey fingernails .i think once you get that carb kit fitted and follow grumpys advice with all the step through procedures he has given you. it will be running as best as possible. grumpy has helped me a lot with briggs repair info as they are more of a tricky bugger than 2 stroke engines. but when they are running sweet its terrific.